Non-interruptable tap and method

ABSTRACT

A method and system for distributing multimedia signals to a subscriber from a headend unit. The multimedia signals are transmitted on a network media as an RF signal. The RF signal is fed to an input terminal of a tap which has an RF circuit that splits the RF signal and distributes to an output terminal. The RF circuit splits the RF signals, and feeds the split signal to a plurality of connectors on the tap&#39;s front panel. The RF signals on the output terminal are fed downstream to a plurality of subscribers. A plate is placed in the tap such that when the RF circuit is removed for repair, maintenance or service, an electrical connection is maintained between the input and output terminal to prevent a disconnection of service downstream.

This application is a continuation of U.S. patent application Ser. No.08/408,605 filed Mar. 21, 1995, U.S. Pat. No. 5,648,745.

BACKGROUND OF THE INVENTION

This invention relates to a method and apparatus for distributingbroadband signals to a subscriber, more particularly the inventionrelates to a tap that splits RF signals, and then distributes thesesplit signals to the home, and specifically the invention relates to atap that can be maintained without interrupting downstream service.

When distributing radio frequency (RF) signals, such as video signals,over cable, it is common practice to transmit RF signals over a coaxialcable through an amplifier to a plurality of passive devices. These RFsignals originate from a central location commonly referred to as the"headend". Passives tap off the RF signal from the cable distributionsystem and feed the tapped off RF signal to various subscriberequipment. With the advent of interactive television, these passivesmust also pass RF signals from the home to the headend (upstream)without interfering with RF signals sent to other passives andamplifiers (downstream). The passive equipment, however, must also passand distribute the RF signal downstream without interfering with thevarious operations that relate to the RF signals.

In today's distribution network, certain other equipment such as networkinterface units (NIU's ) and customer interface units (CIU's ) arecoupled to the home to provide subscriber services to the subscribersuch as voice (i.e. telephony), video, data (i.e. modem and facsimiletransmissions). The NIU and CIU do need the single AC power signal and aseparate RF signal from the passives for its operation. The NIU and CIUbecause they supply telephony, must supply signals to the home in caseof a power failure. Therefore, the NIU and CIU must receivenon-interruptible power.

Prior taps distributed RF signals typically carrying video and voicedata from a central location, called a headend to a plurality ofsubscribers. Typically these taps have frequency ranges of zero to 550MHz. These taps have an input terminal that receives signals from theheadend, and an output terminal where these received signals aredistributed downstream to other taps. Upgrading of the taps to supporthigher frequencies, requires removal and replacement of the circuitinside. Removing the tap circuit temporarily disconnects servicedownstream. When supplying video, a short temporary disconnects ofservice was tolerated by the subscribers. However, taps now send andreceive telephony signals in which a temporary disconnection in serviceis unacceptable.

SUMMARY OF THE INVENTION

An object of this invention is to provide an improved method andapparatus for distributing RF signals carrying voice, data or videoinformation to a subscriber.

It is also object of this invention is to upgrade existing passives witha circuit which splits RF signals and routes these split signals toconnectors on a face plate for distribution to a subscriber withoutinterruption of downstream service.

Another object of this invention is to connect a power distribution unitto an existing tap such that the tap can be upgraded withoutinterrupting service downstream.

These and other objects of the invention are provided with a system fordistributing multimedia information from a headend unit to a subscriber.The system has a network media operative to distribute an RF signal anda tap. The RF signal contains multimedia information originating fromthe headend. Included with the tap is an input terminal coupled to thenetwork media to which the RF signal is fed. The tap has an outputterminal for feeding the RF signal downstream to the subscriber, and aplurality of RF output connectors. Mounted on the tap is a frontsupporting an RF circuit that is removable engagable with the inputterminal The circuit distributes the RF signal on the input terminal tothe output connectors, and the circuit contains a switch thatelectrically shorts said input terminal to said output terminal when thecircuit is disengaged from the input terminal. The switch removes theelectrical short between the input terminal and the output terminal whenthe circuit is engaged with the input terminal thereby preventing adownstream interruption of service.

In another aspect of the invention a method of servicing a tap isprovided. The tap has an input terminal, an output terminal, a pluralityof RF connectors, and an RF circuit on a front portion of the tap fordistributing an RF signal on the input terminals to the RF connectors.When servicing the tap, the front portion of the tap is removed. As thefront portion is removed for servicing, a switch is engaged to connectthe input terminal to the output terminal. Engaging the switch maintainsan electrical connection there between. The switch replaces the RFcircuit to prevent disconnection downstream. When reattaching the frontportion to the tap after servicing or upgrading, the circuit makeselectrical contact with the input output terminals, disengages theswitch and effectively removes the switch from the RF circuit.

The foregoing and other objects of the present invention a well as theinvention itself, may be more fully understood from the followingdescription when read together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is block diagram of a system for distributing video and telephonysignals from a headend unit to a subscriber home in accordance with theinvention;

FIG. 2 is schematic diagram of the passive unit shown in FIG. 1;

FIGS. 3A and 3B are perspective views of a non-interruptible circuitillustrating the principles of the invention;

FIG. 4 is an exploded view of a preferred embodiment of the passiveunit;

FIG. 5 is a perspective view of a retainer shown in FIGS. 3A, 3B and 4;

FIG. 6 is rear view of the front panel of the passive unit shown in FIG.4;

FIG. 7 is a front view of the rear panel of the passive unit shown inFIG. 4; and

FIG. 8 is an exploded side view of the passive unit cut along line 8--8in FIG. 7 with a side view of the front panel shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, there is shown a system 10 for distributing data,sound, and video, generally referred to as multimedia information, froma headend unit 12 to subscribers 14. The headend 12 typically receivesRF signals carrying the multimedia information from a satellite, cable,fiber optic networks, microwave, VHF, UHF, or other sources andtransmits these signals to a subscriber home 14 via distribution network16. Distribution network 16 includes a Hybrid Fiber or Coax network,amplifiers 18 and other distribution equipment that connect headend unit12 with a passive, hereafter referred to as taps 20-20N.

An example tap 20, shown in more detail in FIG. 2, receives an RF signalfrom network 16 on upstream line 25. The RF signal is received on inputport or terminal 50. The RF signal exits tap 20 at output terminal 52.Tap 20 feeds the RF onto downstream line 27 to other devices downstreamof the network 18. Tap 20 splits the composite signal into a pluralityof RF signals.

The split RF signals exits standard F-type connectors or terminals30-36, typically located on a front panel assembly 70 (FIG. 4) of tap20. These split RF signals are respectively fed to a customer interfaceunit (CIU) (not shown) using a coaxial cable. The CIU is typicallylocated on the side of home 14. These split RF signals may be feddirectly to a subscriber set top terminal or other subscriber homecommunications device. The RF signal is fed to tap 20 over a networkcoaxial cable 25. Upon exiting tap 20 on terminal 52, the RF signal isfed to network coaxial cable 27.

Referring to FIG. 2, there is shown a simplified schematic diagram of atap 20 having an input terminal 50 and an output terminal 52. Tap 20 hasrear panel assembly 68 and a front panel assembly 70 (FIG. 4) whichcontains an RF circuit 58. RF circuit 58 contains receptacles 44R and46R that mate with plugs 54P and 56P respectively on assembly 68. Tap 20includes switch 42 electrically coupled in parallel with circuit 58between terminals 50 and 52. Switch 42 opens when front panel assembly70 engages with rear panel assembly 68 and receptacles 44R and 46Rengage with plugs 54P and 56P respectively. Switch 42 closes when frontpanel assembly 70 is removed from rear panel assembly 68 and receptacles44R and 46R disengage from plugs 54P and 56P respectively. The RF signalon input terminal 50 is fed through plugs 54P and receptacle 44R tocircuit 58. RF signals exit circuit 58 though receptacle 46R and plug56P to terminal 52.

Switch 42 contains terminals 54 and 56, and plate 60. Plate 60 throughmechanical means, as will be described later in FIGS. 3 and 4,disengages from terminals 54 and 56 to open switch 42. Plate 60 engageswith terminals 54 and 56 to close switch 42.

Circuit 58 contains a choke 62 with an input terminal 63 and an outputterminal 65 respectively connected to receptacles 44R and 46R. Choke 62is coupled at terminal 63 through capacitor 68 and coupled at its otherterminal 65 through capacitor 70 to coupler circuit 64. Couplercircuitry 64 is coupled through splitter circuitry 66 to outputterminals 30-36. Details of this schematic are described in pending U.S.application Ser. No. 08/297,724 (now U.S. Pat. No. 5,483,208) filed Aug.26, 1994, which is hereby incorporated by reference.

Referring to FIGS. 3A and 3B there is shown a diagram illustrating theprinciples of the invention. Tap 20 (FIG. 4) contains a plate 60 thatextends between terminal 54 and 56. Plate 60 is elongated, thin, flatand constructed from a metal material and curved at its ends 60A and60B. Plate 60 rests on a top terminal support 72 that surroundsterminals 54 and 56 to provide support therefor. When front panel 70disengages (disconnects) from rear panel 68, plate 60 engages withterminals 54 and 56 to electrically short the terminals together.Concurrently with front panel 70 being disengaged, receptacles 44R and46R are electrically and physically disengaged from the top end ofterminals or plugs 54P and 56P, as shown in FIG. 3A.

Resting on plate 60 is a retainer 74. Front panel assembly 70 contains aprotrusion 78, which engages with retainer 74, when front panel assembly70 is engaged with rear panel 68. Upon engaging front panel 70 with rearpanel assembly 68, receptacles 44R and 46R engage with plugs 54P and 56Prespectively to make electrical contact therewith. Simultaneouslyprotrusion 78 forces retainer 74 to slide down into an aperture 80 (FIG.4) in top terminal support 72. As retainer 74 slides downward, plate 60is forced into aperture resulting in the ends of plate 60A and 60Belectrically and physically disconnecting from terminals 54 and 56.

When front panel 70 again disengages from rear panel assembly 68, plate60 springs upward to engage with terminals 54 and 56 to electricallyshort the terminals together. Throughout the removal an electricalconnection is maintained between terminals 54 and 56 preventinginterruption of service to subscribers downstream.

Referring to FIGS. 4, 7 and 8 there is shown a conventional tap 20having a front panel assembly 70 and a rear panel assembly 68.

Referring to FIGS. 6 and 8, mounted on front panel assembly 70 is an RFcircuit board 82 containing circuit 58. Extending away from front panelassembly 70 is elongated protrusion 78. Mounted on the surface ofcircuit board 82 and extending perpendicularly from it are cylindricallyshaped receptacles 44R and 46R. Receptacles 44R and 46R have a springtype inner surface to engage with the top of terminals 54P and 56P.

Referring to FIGS. 4, 7 and 8, rear panel assembly 68 has ports 86, 88,90 and 92 though which line 25 and 27 are adapted to extend therethroughto connect to terminals 54 and 56 respectively. Terminals 54 and 56 aresupported by top terminal support 72 and bottom terminal support 94.Terminals 54 and 56 rotate about their longitudinal axis 96 and 98respectively to connect through lines 25 and 27 entering tap 20 thoughports 86 and 88, or ports 90 or 92. Terminals 54 and 56 have an aperture(not shown) extending through their bottom portion to receive lines 25and 27. A screw (not shown) is also embedded into terminals 54 and 56 tohold lines 25 and 27 in the aperture.

Referring to FIG. 4, top terminal support 72 engages with bottomterminal support 94 to hold terminals 54 and 56 therebetween. Supports72 and 94 connect to rear panel assembly 68 with screws 100 and 102. Topterminal support 72 has an aperture 106 and 108 though which terminals54 and 56 extend therethrough. Support 72 has a center aperture 80 (FIG.4) that receives retainer 74. Elongated rectangular plate 60 rests onsupport 72 and is held in place with retainer 74.

Referring to FIG. 5, retainer 74 has a top engaging surface 110 and fourlegs 112-118 extend downward therefrom. At the bottom of each leg112-118 are lips 120-126 respectively which engage with a back surfaceof support 72. Legs 112-118 flex inwardly toward each other whenengaging with support 72, and then flex outwardly after engagement. Thebottom of surface 110 slopes inward and downward to a point 132 to urgeplate 60 into aperture 80.

It is preferable that assemblies 68 and 70 are constructed from anonmagnetic metal material. Assemblies 68 and 70 have a plastic orrubber type gasket material, as is known in the art, attached to theirsurfaces where the assemblies contact each other to prevent waterleakage. It also preferable that an EMI gasket material is positionedadjacent the gasket material to prevent RFI leakage.

While the principles of the invention have been made clear in theillustrated embodiments, there will be immediately obvious to thoseskilled in the art, many modifications are structured arrangementsproportions, elements, materials, and components used in the practice ofthe invention, in otherwise which are particularly adapted for specificenvironments and operational requirements, without departing from thoseprinciples. The appended claims are therefore intended to cover andembrace any such modifications within the limits only of the true spiritand scope of the invention.

What we claim are:
 1. A tap for distributing an RF signal onto a networkmedia to subscribers, the tap comprising:an input terminal coupled tosaid network media to which said RF signal is fed; an output terminalthrough which the RF signal is passed; a plurality of RF outputconnectors; a circuit, removably engagable with said input and outputterminal, operative to distribute the RF signal on the input terminal tothe output connectors, wherein the circuit has a pair of members thatengage with the input and output terminals as the circuit engages withthe input and output terminals; and a switch means for ensuring anelectrical connection is maintained between said input terminal and saidoutput terminal while said circuit is disengaged from said terminals toprevent the interruption of signals to subscribers by electrically shortcircuiting said input terminal to said output terminal before saidcircuit is disengaged from said input terminal, and for removing theelectrical short circuit between said input terminal and said outputterminal when said circuit is engaged with said input terminal.
 2. Thetap as recited in claim 1 wherein said terminals having a longitudinalaxis extending therethrough and said terminals are rotatable about thelongitudinal axis.
 3. A tap for distributing an RF onto a network mediato subscribers, the tap comprising:an input terminal coupled to saidnetwork media to which said RF signal is fed; an output terminal throughwhich the RF signal is passed; a plurality of RF output connectors; acircuit, removably engagable with said input and output terminal,operative to distribute the RF signal on the input terminal to theoutput connectors; a switch means for ensuring an electrical connectionis maintained between said input terminal and said output terminal whilesaid circuit is disengaged from said terminals to prevent theinterruption of signals to subscribers by electrically short circuitingsaid input terminal to said output terminal before said circuit isdisengaged from said input terminal, and for removing the electricalshort circuit between said input terminal and said output terminal whensaid circuit is engaged with said input terminal, wherein said switchmeans includes a flexible electrically conductive plate extendingbetween said input and output terminal operative to physically contactsaid input and output terminals when said circuit is disengaged fromsaid input terminal and to disengage from said input terminal when saidcircuit is engaged with said input terminal; a support disposed betweensaid input and output terminal for holding said plate; and a memberslidably engagable with said plate when said circuit is disengaged fromsaid input terminal, said member operative to depress a section of saidplate to disconnect said plate from said input terminal when saidcircuit is engaged with said input terminal.
 4. A tap for distributingpower and radio frequency (RF) signals from a cable comprising:a firstterminal operative to couple to the cable through which the RF signalsare fed; a second terminal through which the RF signals are fed to asecond cable; said terminals having a longitudinal axis extendingtherethrough and said first and second terminals being rotatable aboutthe longitudinal axis; a plurality of RF output connectors; a circuitremovably engagable with said first terminal; said circuit, when engagedwith the first terminal, being operative to split the RF and powersignal on the first terminal and to feed the split RF signal to the RFoutput connectors, and being operative to feed the RF and power signalon the first terminal to the second terminal; and a plate for engagingwith said first terminal to electrically short said first terminal tosaid second terminal when said circuit is disengaged from said firstterminal, and for disengaging from said first terminal to remove saidelectrical short between said first terminal and said second terminalwhen said circuit is engaged with said first terminal; a rear panelholding said first terminal and said second terminal; and a front panelattached to said circuit and supporting said RF output connectors. 5.The tap as recited in claim 4 further comprising:a support membersubstantially extending between said input and output terminal andholding said plate; and a slidable member in contact with said supportmember and having a surface to depress said plate when said front panelis connected to said rear panel.
 6. The tap as recited in claim 5wherein said support member has a top engaging surface to hold saidplate between said terminals.
 7. The tap as recited in claim 6 whereinsaid support member is shaped to permit said plate to flex when saidslidable member depresses said plate and disengage from said inputterminal.
 8. A method for distributing RF signals on a network mediausing a tap, the method comprising the steps of:providing a rear panelhaving a first pair of ports, a second pair of ports, and an inputterminal and an output terminal, each terminal being rotatable about alongitudinal axis extending therethrough; extending the network mediathrough the first ports or the second ports; rotating the input terminaland the output terminal about their longitudinal axis to hold theextended network media in electrical contact therewith; providing afront panel having a plurality of RF output connectors; attaching to thefront panel a circuit having a pair of members operative to mate withthe input and output terminal; providing an electrical short circuitbetween the input terminal and the output terminal; assembling the tapby attaching the rear panel to the front panel and by engaging themembers with the input terminal and the output terminal to electricallyconnect the circuit to the network media; splitting RF signals on theinput terminal with the circuit on the assembled tap and transmittingthe split RF signals to the RF output connectors; and removing theelectrical short circuit when the members electrically connect thecircuit to the input terminal and the output terminal.